Theoretical insights into the impact of hydrogen bonding interactions and proton-transfer phenomena on the excited state of HBT-TMS fluorophore: Solvent-induced effects

Inspired by the design of distinguished optical materials, novel organic molecules exhibiting excited state intramolecular proton-transfer (ESIPT) characteristics have emerged as a prominent research topic. In this study, we focus on investigating the excited state dynamics of 2-(5-trifluoromethyl-benzothiazol-2-yl)-4,6-bis-trimethylsilanylethynyl-phenol (HBT-TMS), a novel color-tunable multifunctional ESIPT emitter. By considering four different aprotic solvents with varying polarities, we confirm the influence of solvent polarity on photo-induced hydrogen bonding interactions, charge redistribution, and associated ESIPT phenomena. Through comparison and quantification of the magnitudes of excited state reaction barriers in different solvents, our findings suggest that highly polar solvents facilitate the ESIPT reaction for HBT-TMS fluorophore. Solvent-polarity-dependent ESIPT behavior for HBT-TMS fluorophore. image